PAC staircase system is made of Lattice girder beams, PAC blocks, cross ribs and steps that can be obtained by sawing of PAC blocks thickness of 30 or 40 cm, or can be constructed with normal concreting of the framework. With this system it is necessary to incorporate additional reinforcement joints beams as transverse ribs, in the place of appropriate transverse direction to main beam girder. Reinforcement of supporting beams is designed solely on the basis of structural analysis.